Magnetic switch



Jan. 16, 1962 N. VERGER ,47

MAGNETIC SWITCH Filed July 2, 1958 2 Sheets-Sheet 1 III/III All! //Vl /V7'0/e NATHAN VERGER Jan. 16, 1962 N. VERGER 3,017,473 MAGNETIC SWITCH Filed July 2, 1958 2 Sheets-Sheet 2 H U NATHAN VERGER 7s I INVIENTOR. 73 74 WWW,

United States Patent 3,017,473 MAGNETIC SWITCH Nathan Verger, Great Neck, NY. (26 Court St., Brooklyn 1, NY.) Filed July 2, 1958, Ser. No. 746,278 1 Claim. (Cl. 200-87) This invention relates to a switch and more particularly to a magnetic switch especially adapted for use in conjunction with burglar ala-rm circuits.

Magnetically-operated switches have a wide field of application. Such switches are however particularly useful in conjunction with burglar alarm circuit arrangements. In the installation of burglar alarms, it is often desirable to utilize switches in which there is no physical contact between the switch element and the actuating device, particularly to indicate the displacement of one body from another. Thus, more specifically, a switch of this character finds particular utility as applied to a doorway or window wherein the switch unit is advantageously secured to a fixed body such as a door or window jamb and its associated actuating unit is mounted upon a relatively movable element such as a door or window sash. In this type of switch application, the two units of the switch arrangement are disposed in juxtaposition ,while the window or door is closed, thereby maintaining the switch in actuated condition. The movement of the window sash or door by unauthorized persons results in a displacement of the actuating unit from the switch unit thereby releasing the switch from its actuated condition and thus causing it to assume an alternate position, for the further actuation of any devices which may be as sociated therewith. The use of magnetic switches in connection with such arrangements is well known in the art. However, in order to achieve effective operation, it, is essential that a magnetic switch of this character cause a positive actuation of the switch contact elements when the magnetic actuating unit is brought into operative relation with the switch unit; and that it retain the switch contact elements in operated condition in spite of vibration or extensive displacements of the units from each other when not caused by an unauthorized entry into the premises. Furthermore, it is highly desirable that the arrangement be such that the changes in'the physical relationship between the fixed and movable structures, such as the warpage of a door, should not affect the operation of the device within reasonable limits.

In order to accomplish these and other purposes, it is an object of this invention to provide a magnetic switch arrangement wherein electrical contacts are opened and/ or closed by reason of the proximal position of a magnet, and wherein a degree of misalignment between the switch and the magnetic actuator may be tolerated without affecting the efiicient function of the device. I

It is also an object of this invention to provide a magnetic switch arrangement which is freeof chatter and con tact bounce and wherein the electrical contacts are maintained under constant spring tension in spite of tolerable variations of the magnetic actuating field.

' Another object of this invention is to provide a switch arrangement wherein a wiping contact action is provided for the purpose of assuring effective electrical continuity and long contact life for the switch elements.

An additional object of this invention is to provide an arrangement which may be readily and economically manufactured, particularly by metal stamping methods and which may be readily mounted within a housing of a plastic or similar material by economical and eflicient assembly methods.

' 'A further object of this invention is to provide a magnetic switch arrangement wherein the switch is main- 3,017,473 Patented Jan. 16, 1962 tained in actuated condition in spite of the movement of the magnetic actuator within determinable limits so as to prevent the accidental deactuation of the switch.

It is also an object of this invention to provide a switch arrangement wherein the switch and magnetic actuating units may be mounted in various positions with relation to each other.

In order to accomplish these and other objects, there is provided a plastic housing within which there is disposed a pair of fixed or stationary contacts and a pivotally-supported armature carrying a movable contact. There is further provided a fixed armature extension for abutment with the free end of the armature in order to complete the magnetic circuit in a more effective manner. A magnetic actuator unit, mounted within a similar plastic housing, is adapted to be brought into proximal relation with the armature and the fixed extension thereof in order to eifect the actuation of the switch unit.

Other and further objects, benefits and advantages of this invention will appear from the annexed drawings, specification and claim or will otherwise become obvious.

In the accompanying drawings:

FIGURE 1 is a bottom view of the actuating unit with the bottom panel removed in part;

7 FIGURE 2 is a bottom view of the switch unit with the bottom panel removed revealing the switch mechanism; the switch being in unactuated condition;

FIGURE 3 is a c1oss-section of FIGURE 1 taken along line 3-3 thereof showing the bottom panel in position;

FIGURE 4 is a cross-section of FIGURE 2 taken along line 4-4 thereof showing the bottom panel in position;

FIGURE 5 is a view similar to FIGURE 1 wherein the magnetic actuating unit is in proximal relation with the switch unit, said switch unit being therefore in actuated condition;

FIGURE 6 is a fragmentary side elevational view of the switch unit showing the terminal screws for external electrical connections;

FIGURE 7 is an exploded view on an enlarged scale more clearly illustrating the switch members; and

FIGURE 8 is an exploded view, on an enlarged scale, showing the flexure of the armature and contact spring as the armature is moved from unactuated to actuated position.

As may be seen from FIGURES 14, the magnetic switch arrangement comprising the present invention includes a switch unit designated generally by the numeral 10 and an actuating unit designated generally by the numeral 11. Actuating unit 11 comprises a rectangular housing 33 provided with a top wall 12, side walls 13 and 20, and end walls 14. The housing is enclosed by means of a removable bottom panel 15 which completes the enclosure of the housing. A bar of permanently magnetic material 16 is disposed within housing 11 and is retained in position against one of the side walls 13 by means of posts 17 which extend inwardly from the top wall of the housing and form abutments for said bar magnet 16. The bar magnet 16 may be formed of any suitable permanent magnetic material, it being preferred to utilize an Alnico magnet for this purpose. It should be noted that the poles 18 of the magnet are disposed adjacent the end walls 14 of the housing and that said magnet extends along the length thereof bearing against the interior face of the confronting side wall 13. Actuating unit 11 is further provided with fixed bottom wall extensions or ears 19, which are provided with apertures wherein screws or similar fastening means may be inserted for the purpose of mounting the actuating unit upon a support.

Switch unit 10 is mounted in a housing 34 similar to the external construction of the actuating unit housing and is provided with a top wall 21, side walls 22 and 23, end walls 24, and a removable bottom panel 25. A portion of the interior surface of side wall 22 is enlarged, as shown at 26 and has formed therein inwardly extending key slots 27, 23 and 29. The diagonally opposed interior surface of side wall 23 is formed with an inwardly extending slot 30. Abutments 31 and 32 disposed on the interior surface of top wall 21 extend into the interior of the housing. The housings 33 and 34 are advantageously formed of an electrically insulating synthetic resin or plastic material. By this means, a housing of non-magnetic and electrically non-conductive material is provided with appropriate abutments and keyways integrally moulded therein for the purpose of mounting the switch members in a most efiicient and economical manner suitable for large scale production and requiring a minimuln amount of adjustment as will more clearly appear hereafter.

As may be seen from FIGURES 2, 3 and 7, the switch mechanism comprises a number of metallic members which may be advantageously formed by the stamping process from soft steel or similar materials. Said switch mechanism comprises an armature supporting bracket 35 which is provided with a horizontal base portion 36 and a vertical side wall portion 37 disposed in normal relation thereto, to form a substantially L shaped member. A portion of side wall 37 is pierced and deflected to form an anchor hook 38 adapted to engage with the looped end 39 of restoring spring 40. Said side wall 37 is also provided with a screw-threaded aperture 41 which is adapted to receive a terminal screw. The base 36 of the armature supporting bracket 35 is also provided with a vertically disposed pivot pin 42 upon which the armature pivots, as will more clearly appear hereafter. Indentations 43 are provided along each of the side edges of base 36 so that the armature supporting bracket 35 may be mounted in the housing 34 by merely inserting the upstanding portion 37 thereof into key slot 27, the indentations 43 providing adequate clearance to permit such insertion in spite of the uniform width of the strip from which the supporting bracket 35 is formed.

In order to secure the armature supporting bracket in position, it is merely necessary to pass the shank of terminal screw 57 through an aperture provided in side wall 22 and to threadedly engage said screw with the threaded aperture 41 in the side wall whereby the supporting bracket is firmly and securely retained in position. The switch mechanism is further provided with a pair of fixed or stationary contacts 44 and 45. Said stationary contacts comprise a front contact 44 and a back contact 45. Front contact '44 is supported by means of a U shaped stamped metallic bracket 46 having a horizontal base wall 47 and vertical side walls 48 and 49. Side Wall 49 is provided with a terminal screw receiving threaded aperture 50. It will be noted that the base wall 47 and side wall 48 are of narrower dimensions than the side wall 49, so that side wall 49 may be readily inserted in key slot 28 and secured in position by means of the threaded engagement of terminal screw 51 in aperture 50, thereby securing said front contact supporting bracket in position within the housing.

Fixed or stationary back contact 45 is supported by means of horizontally extending supporting bracket 59, which is substantially Z shaped and comprises a pair of side walls 52 and 53 respectively interconnected by means of a web portion 54. A threaded aperture 55 is provided in side wall 53 adapted to receive a terminal screw 56 which is passed through an aperture in the side wall 22 of the housing and threadedly engages said back contact supporting bracket 59 which is disposed within slot 29 formed in the enlarged wall of the housing. The end of said side wall 53 is disposed in slot 29 while side wall 52 bears against abutment 32. It will be noted that with the front and back contact supporting brackets 46 and 59 in position, the contacts 44 and 45 are disposed in confronting horizontally spaced apart relation so that the movable contact 58 may be disposed for lateral movement therebetween.

The armature 60 is formed of a flat strip of ferromagnetic material having a low magnetic retentivity and comprises an arm 61 having a free end 62 and a hinged end 63. The hinged end 63 of the armature is formed by deflecting the material thereof to form laterally extending ears 64. Laterally extending ears 64 are provided with aligned apertures 65 within which a vertically disposed pivot pin 42, preferably formed of a non-magnetic material, such as brass, is received. There is thus provided a pivotal or hinged connection between the supporting bracket 35 and the armature 60 whereby said armature pivots in a horizontal plane passing through axes of contacts 44 and 45 and normal to the axis of pivot pin 42.

Contact spring 66 is secured to the hinged end 63 of armature 66 adjacent the pivotal axis thereof. Said contact spring comprises a substantially Z shaped member having oppositely deflected terminal portions 67 and 68 connected by a body portion 69. Terminal portion 67 is fixedly secured to the hinged end 63 of arm 61 as by means of rivets 70. The opposing free terminal portion 68 of contact spring 66 is disposed in the space intermediate contacts 44 and 45 and carries a double-faced movable contact 58. The fixed terminal portion 67 of the contact spring 66 is also provided with a projecting hooked tongue 71 to which restoring spring 40' is secured by means of an end loop 72. It will be apparent from the foregoing that when the armature 60 is mounted upon pivot pin 42, the pivotal movement of an arm will selectively bring the movable contact 58 thereof into engagement with contact 44 or 45 to thereby provide electrical continuity between the selected contact. In view of the biasing action of restoring spring 40, the contact 53 is normally held in engagement with the stationary back contact 45. Upon pivotal movement of the armature against the biasing action of restoring spring 40, the contact 58 is moved laterally in a plane normal to the pivot axis of the armature. The contact with contact 45 is thus broken and contact is made with the stationary front contact 44.

Disposed within housing 34 in surface contact with the side wall 23 thereof is a fixed armature extension plate 73. Extension plate 73 comprises a strip formed of a ferromagnetic material such as the material of which armature 60 is formed and is mounted in position by insertion of the end thereof in slot 30, said plate being further retained in position between abutment 31 and the side wall 23 of the housing. It will be apparent from FIGURE 2 that a magnetic air gap indicated by the numeral 74 is thus formed between the free end 62 of the armature arm 61 and the end portion of extension plate 73. It will further be noted that the hinged armature and the stationary plate are disposed in oflset relation and so dimensioned that their terminal portions are in confronting relation and overlap each other in the region of air gap 74.

With the actuating unit 11 in a distal position out of operative relation to the switch unit 10, the position of the armature is as that illustrated in FIGURE 2. It will be noted that the movable contact 58 carried by the armature 60 is in engagement with the back stationarycontact and is held in that position under the biasing action of the restoring spring 40. However, when the actuating unit 11 is brought into proximal relation to the switch unit, as shown in FIGURE 5, the armature is drawn against the stationary extension plate 73 and the free end thereof is moved into abutting cont-act with the end of said plate in overlapping relation as shown at 75. The armature and extension thereof thus form a continuous magnetic circuit for the magnetic flux of the permanent magnet disposed within the actuating unit and a positive closure of the switch is effected.

In closing the switch, a wiping contact is made by action may best be seen in FIGURE 8, wherein the armature andthe contact spring carried thereby are shown in broken lines in the course of movement to the closed or actuated position which is shown in full lines. When the armature 60 and contact spring 66 carried thereby reach the broken line position of FIGURE 8, initial contact is made between the front contact "44 and movable contact 58. As the armature proceeds to its fully actuated or closed position, wherein it contacts the stationary armature extension 73, the contact spring 66 is flexed and causes the contact 58 to move along or wipe the surface of contact 44. Furthermore, by reason of the arrangement, contact 58 is held under the constant spring pressure of contact spring 66 when thenarmature is fully actuated. Consequently, a firm contact is established between the contacts 44 and 58 assuring effective electrical continuity.

It should be further noted that contact spring 66 is secured to the armature end adjacent the hinged portion thereof and that the free terminal end carrying contact 58 is disposed substantially intermediate the ends of the armature arm 60, so that a substantial mechanical advantage is developed by reason of the extended length of the armature arm, thereby permitting the movement of said armature to more readily overcome the spring tension of contact spring 66 and again assuring a positive and firm contact with the front contacts 44.

Similarly, it should be noted that the hooked tongue 71, to which restoring spring 40 is secured at one end thereof, is also disposed adjacent the pivot pin of the armature hinge. Since the opposing end 39 of the restoring spring 40 is secured to anchor hook 38, which is in alignment with the pivot point of the hinge, it is apparent that the mechanical advantage provided by the elongated armature arm is also effective to overcome the biasing action of the restoring spring. However, with the switch, in the course of movement to open or unactuated position, the restoring spring will cause a degree of flexure in the contact spring 66 which, together with the movement of the armature, will cause a wiping contact to be made with the back contact 45, thereby assuring long contact life and effective electrical continuity. The restoning spring causing a slight flexure assures that the contact spring will retain movable contact 58 in firm elec trical contact with back contact 45 under the biasing action thereof when the switch is in unactuated position. Thus, the switch arrangement assures an effective singlepole, double-throw switch action.

A significant feature of the invention resides in the provision of the hingedly movable armature in association with a stationary armature extension of substantially similar physical configuration which forms a continuum thereof. It has been found that the arrangement, when used in conjunction with a bar magnet which is brought in confronting relation with the planar fixed and movable armature surfaces, is particularly effective for providing positive magnetic actuation for the switch. The bar magnet is advantageously dimensioned so that the poles thereof are brought into confronting relation with the hinged end of the movable armature and the distal end of the stationary armature extension. Under these circumstances, an effective magnetic circuit is established between the poles of the magnet through the two armature sections.

Thus, when the actuating unit is brought into proximal relation to the switch unit, the hinged armature readily moves toward closed position and as the air gap is reduced increasing magnetic force is applied until abutting contact is made between the stationary and movable armatures, completely eliminating the air gap. It has been found that this action effectively prevents the movable armature from hanging as contact is made between the front contact and the movable contact elements and the contact spring tends to resist the further movement of the armature. The arrangement also prevents any contact bounce or chatter which might result without the application of the positive closing action herein provided. Furthermore, by reason of the arrangement, it has been found that considerable misalignment may be tolerated between the actuating unit and the switch unit without affecting the positive action of the switch. It has been found that once the actuating unit is brought into sufficient proximity to the switch unit so that armature movement is initiated, a complete closure of the armature will be effected in a positive manner. By the same token, the switch having been actuated, will be maintained in actuating condition in spite of a certain amount of vibration or displacement of the units from each other, which is encountered in use and which would effect an undesired opening of the switch. Conditions of this character are encountered as when the switch is used in conjunction with a burglar alarm circuit attached to a door. Under such conditions, the units may be moved out of alignment as a result of physical changes, such as the warpage of a door which would normally require the repositioning of the switch or actuating unit. Similarly, a door may be subject to vibration which does not amount to an unauthorized entry and which would result in a false alarm or undesired opening of the switch contact unless tolerated by the switch arrangement.

Furthermore, the instant arrangement, wherein an ex-, tended magnetic circuit is provided in the switch unit, permits the location of the actuating unit in various positions with respect to the switch unit without sacrifice of effective switching action. The switch arrangement makes highly efiicient use of the magnetic flux field and permits effective switching action without absolute alignment of the units and even in angular dispositions one with respect to the other.

The switch arrangement herein disclosed is highly depend-able in operation. Having been closed by the actuating unit, the contacts remain closed without any reduction or variation in contact pressure. This condition continues in spite of relatively extensive movement of the actuating unit away from the switch unit. Although the operation of the switch unit requires that the actuating unit be brought into relatively close proximity therewith for actuation, the switch having been actuated will remain in such condition in spite of the withdrawal of the actuating unit to a much greater distance. In burglar alarm applications it is essential that the switch be initially actuated only upon the complete closure of the door to eliminate the possibility of the door being unwittingly left open. Thereafter, however, the switch should and does remain actuated and the contacts are held with uniform contact pressure under the tension of the contact spring in spite of a movement of the actuating unit a considerable distance thus providing uninterrupted continuity through the switch. When the critical distance is exceeded, the switch contacts break cleanly and movable contact returns completely to its unactuated condi tion. The ability to tolerate the movement of the actuating unit, particularly to a considerably greater distance than the point at which actuation occurs and to maintain full contact pressure during such movement and for said distance, is a particularly desirable feature in burglar alarm applications.

I have here shown and described a preferred embodi: ment of my invention. It will be apparent, however, that this invention is not limited to this embodiment, and that many changes, additions and modifications can be made in connection therewith without departing from the spirit and scope of the invention as herein disclosed and hereafter claimed.

I claim:

A magnetically-operated switch comprising a switch unit and an actuating unit, said switch unit comprising a housing of non-magnetic material, switch mechanism disposed within said housing, said housing comprising an enclosure having a top wall, side and end walls and a bottom panel, a portion of one of said side walls being enlarged and provided with a plurality of key slots, said switch mechanism comprising an armature supporting bracket having a horizontal base portion and a vertical side wall, said side Wall being received within one of said key slots and being provided with an outwardly extending anchor book, a pivot pin carried by the base portion of said bracket and extending vertically therefrom, an armature pivotally carried by said bracket, said armature comprising an arm, one .end of said arm being provided with laterally extending apertured ears, said pin being received Within the apertures of said ears whereby said armature is mounted for pivotal movement in a plane normal to the axis of said pin,.a contact spring having a body portion and oppositely deflected end portions, one of said end portions being provided with projecting tongue and being secured ,to said armature adjacent the pivoted end thereof, the other end of said contact spring being provided with an electrical contact element whereby said contact element is movable correspondingly with the pivotal movement of said armature, a restoring spring having the ends thereof secured to said anchor hook and said tongue, a front stationary contact and a back stationary contact disposed in operative relation With respect to said movable contact element, a bracket for supporting said back contact, said bracket comprising a substantially Z-shaped element provided with a web portion and oppositely deflected side Walls, one of said side walls being received in one of said key slots and the other side wall supporting said back contact element, said front contact being carried by a U-shaped supporting bracket provided with a horizontal base wall and vertically extending side walls, one of said side. walls being received in one of said key slots and the other of said side walls supportingsaid front contact element, said front and back contacts being disposed in spaced. alignment so that the movement of said movable contact element alternately contacts one or the other of said stationary contacts, a stationary armature extension disposed along the diagonally opposed portion of the other side Wall of said housing, said extension comprising a strip of ferromagnetic material disposed in offset relation with respect to the free end of said armature to form an air gap therebetween when said armature is in its unactuated position and to make contact with a portion of said armature when said armature is in actuated position; said actuating unit comprising a housing of non-magnetic material, a bar magnet disposed within said housing, said units when brought into proximal relation causing said bar magnet to overlie said armature and the extension thereof, thereby actuating said armature.

Winterburn Feb. 9, 1960 

